This section provides information helpful in understanding the invention but that is not necessarily prior art.
Flexible packaging includes a wide variety of materials such as various plastic films, laminates, and foil that extend the shelf life and protect many products, such as food products. In order to extend the shelf of a food product the food product is packaged and subjected to pasteurization or sterilization using high temperatures, high pressure, or both (retort process) to destroy bacteria.
Retort ink systems have been known for some time in gravure printing. However, due to the necessary pigment load and solvency of the resin required so as not to swell flexographic plates, development of retort inks for flexographic printing has been limited. Despite prior efforts, there remains a need for an improved flexographic ink for printing on flexible packaging material that provides high lamination bond strength when subjected to high temperature or pressure processing, such as in a retort process.